https://service.tib.eu/vdataset/inspirehep_fb9b3ec7-675d-4873-bbd6-4420f0717cc2 Georges Aad Braden Keim Abbott D.C. Abbott Kira Abeling Haider Abidi Asmaa Aboulhorma Halina Abramowicz Henso Abreu Yiming Abulaiti A.C. Abusleme Hoffman Not defined 2025 Georges Aad 17/11/2025 17/11/2025 Dataset 0 kb A measurement of single top-quark production in the s-channel is performed in proton--proton collisions at a centre-of-mass energy of $13$ TeV with the ATLAS detector at the CERN Large Hadron Collider. The dataset corresponds to an integrated luminosity of 139 fb$^{-1}$. The analysis is performed on events with an electron or muon, missing transverse momentum and exactly two $b$-tagged jets in the final state. A discriminant based on matrix element calculations is used to separate single top-quark s-channel events from the main background contributions, which are top-quark pair production and $W$-boson production in association with jets. The observed (expected) signal significance over the background-only hypothesis is 3.3 (3.9) standard deviations, and the measured cross-section is $\sigma=8.2^{+3.5}_{-2.9}$ pb, consistent with the Standard Model prediction of $\sigma^{\mathrm{SM}}=10.32^{+0.40}_{-0.36}$ pb.